<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>

    <style>
        /*margin: 0 auto;*/
        /*居中要求：必须是块元素，块元素有固定的宽度*/
        div{
            width: 300px;
            margin: 0 auto;
        }
        img{

            border-radius: 320px ;
            box-shadow: 10px 10px 100px yellow;
        }
    </style>

</head>
<body>
<div>
    <img src="images/img.png" alt="">
</div>

</body>
</html>